In the past weighing devices or scales have been constructed in many manners. Most scales have a series of levers and knife edges which transfer force to produce measurable readout. Scales employing knife edges have several disadvantages: friction and wear at the knife edges requires constant maintenance and calibration, the knife edge is subject to damage from lateral forces, and sensitivity to nonhorizontal positions. Also, the production of a lightweight portable scale capable of handling a heavy load has been difficult because of the great stress placed on the relatively small knife edges for load borne by them. Furthermore, portable scales employing knife edges are particularly susceptible to inaccurate readings resulting from canting of the scale off level.
Presently, there is a substantial demand and need for a lightweight, reliable, easily maintained portable scale. Such scales are especially in demand by law enforcement agencies desiring to check the weight of trucks. The scales are also useful in many other applications, such as the weighing of airplanes to determine proper load balance. When scales are used for high volume weighing, such as trucks on the highway, there is a special need for a scale which gives a dynamic readout which does not require the complete stop of a vehicle to obtain an approximation of the load weight. Thus, vehicles clearly within weight limits may proceed without actually stopping; whereas, those at a questionable weight limit can be stopped and weighed more accurately in a static position.
Further, there is a need for a very durable lightweight scale that can withstand abuse from users. For example, a common occurrence in the weighing of trucks is that the truck driver pulls the truck onto the scale and then rapidly applies the brake, creating considerable lateral forces on the scale. This can either severely damage or destroy scales incorporating knife edges.
The present invention provides a portable scale that can provide dynamic or static measurements, is relatively maintenance free, highly durable, and highly reliable.